Newly formed Tropical Storm Nate has been blamed for at least 22 deaths across Central America as it dumped rain across the region on a path that would carry it towards a potential landfall on the US Gulf Coast as a hurricane.

It had maximum sustained winds of 65kph and was likely to strengthen over the north-western Caribbean Sea on Thursday night (local time) before a possible strike on the Cancun region at the tip of Mexico's Yucatan Peninsula.

In Nicaragua, Nate's arrival followed two weeks of near-constant rain that had left the ground saturated and rivers swollen.

Authorities placed the whole country on alert and warned of flooding and landslides.

Nicaragua's Vice-President and spokeswoman, Rosario Murillo, said at least 15 people had died in that country due to the storm.